SEX PHEROMONES AND CONJUGATION IN STREPTOCOCCI

这项拟议工作的主要目标是表征关键分子 粪链球菌中与性信息素相关的交配系统。 人们的注意力将集中在性信息素的产生上 受体和对这种信息素的反应 含有质粒的供体。研究的部分内容将利用 最近鉴定的转座子Tn916和Tn917。更具体地说，我们 将：1)对PAD1信息素反应进行遗传分析，利用 Tn917作为插入诱变剂和大肠杆菌-链球菌“穿梭” 载体“，用于克隆和遗传分析所选的质粒片段； 2)识别由质粒编码(受控)的蛋白质和RNA物种 在cad1信息素反应过程中诱导，并试图将 从遗传研究中发现的PAD1决定因素的蛋白质；3)产生 粪链球菌不能分泌cPD1的突变体，检测它们的 能够排泄其他信息素，并表现为接受者，并使用 探索信息素前体多肽的可能存在；4) 克隆和测序据信含有该结构基因的DNA片段 性信息素；5)纯化和鉴定cad1和cpd1，并尝试 将它们的氨基酸序列与克隆的基因组DNA碱基序列相关联；6) 确定性信息素的产生在以下情况下被关闭 通过分析新发现的编码修饰的质粒来获取质粒 Cad1和cpd1的形式；以及7)使用粪链霉菌“响应者”小组 菌株，筛选其他细菌种的培养滤液中的信息素 活动。

The primary objective of the proposed work is to characterize key molecular aspects of sex pheromone-related mating systems in Streptococcus faecalis. Attention will be focussed on both the production of sex pheromones by recipients and the response to such pheromones by certain plasmid-containing donors. Parts of the study will make use of the recently characterized transposons Tn916 and Tn917. More specifically we will: 1) Genetically analyze the pAD1 pheromone response, making use of Tn917 as an insertional mutagen and an E. coli-streptococcus "shuttle vector" to clone and genetically analyze selected segments of the plasmid; 2) Identify plasmid-encoded (controlled) protein and RNA species that are induced during the cAD1 pheromone response and attempt to relate the proteins to pAD1 determinants revealed from genetic studies; 3) Generate mutants of Streptococcus faecalis that fail to excrete cPD1, examine their ability to excrete other pheromones and to behave as a recipient, and use them to explore the possible existence of pheromone precursor peptides; 4) Clone and sequence segments of DNA believed to contain the structural gene for sex pheromone; 5) Purify and characterize cAD1 and cPD1 and attempt to relate their amino acid sequences to cloned genomic DNA base sequences; 6) Determine the nature by which sex pheromone production is shut off after plasmid acquisition, by analyzing newly discovered plasmid encoded modified forms of cAD1 and cPD1; and 7) Using a panel of S. faecalis "responder" strains, screen culture filtrates of other bacterial species for pheromone activity.